The present invention relates generally to aircraft turbofan engines, and, more specifically, to exhaust nozzles therefor.
Thrust reversers that integrate variable exhaust nozzles are known in the art. A typical example of a target reverser with throat adjustment capability is described in U.S. Pat. No. 5,181,676. It is composed of a fixed structure 34 (reference numbers are those in the patent) commonly called jet pipe, on which are hinged a pair of thrust reverser doors 30 and a pair of shells 44. When the reverser doors 30 are stowed, the pair of shells 44 cooperate with the pair of thrust reverser doors to ensure that the exhaust nozzle is planar.
The pivots 40 of the reverser doors, which are linked to the corresponding pivots 58 of the shells via arms 56, have the capability of undergoing radial and longitudinal displacements that confer area adjustment capability to the throat of the exhaust nozzle. The nozzle exhaust area variation capability allows, in forward thrust mode, the adjustment of the exhaust area to the particular value required for achievement of optimum performance for the particular flight conditions.
In this prior art patent the adjustment of the throat area of the nozzle is performed by actuation means 50, while the deployment of the thrust reverser is performed by different actuation means 52. The use of a dedicated actuation system 50 for the variable nozzle function of the apparatus described has also the advantage of allowing the locking of the thrust reverser door pivots in their most rearward position while the reverser doors, by actuation means 52, are deployed and during their travel from their deployed position to their stowed position.
The locking of the reverser door pivots during the stowing mode of the reverser is necessary so that the latch receptacle 66 can re-engage the latch arm 54. If previous mentioned locking of the pivots of the thrust reverser doors is not performed prior to moving the reverser from its deployed position to its stow position, then the dedicated actuation system 52 of the reverser doors would rotate and forwardly translate the pivots of the reverser and consequently prevent its complete stowing as its latch receptacles 66 would miss their respective target 54.
While the use of a dedicated actuation means for varying the area of the exhaust nozzle and the use of a second actuator means for deploying the reverser is mechanically attractive by its simplicity, experience shows that the space required for installation of these dedicated actuation means is often not compatible with the available space.
A first desired object is to overcome the drawbacks of prior art jet engine variable nozzles integrated to thrust reversers, and to use the same actuation means for performing the adjustment of the value of the exhaust area of the nozzle and for performing the deployment/stowing of the thrust reverser.
A second object is to provide, for forward thrust mode, fixed retainers for keeping the reverser in its stowed position.
A third object is to give, for forward thrust mode, the capability to previous fixed retainers to accommodate the longitudinal and radial motions of the reverser nozzle assembly, for adjustment of the value of the exhaust area of the nozzle.
A fourth object is to configure previous fixed door retainers such that the reverser doors, for deployment purpose, can only disengage the fixed retainers once the doors have moved downstream of the position corresponding to the value of maximum area of the exhaust nozzle.
A fifth object is to provide, in forward thrust mode, a locking means of the position of the reverser nozzle assembly, when the value of the exhaust area of the nozzle is minimum.
A sixth object is to provide, in forward thrust mode, a locking means of the position of the reverser nozzle assembly, when the value of the exhaust area of the nozzle has reached its maximum.
A seventh object is to allow, for forward thrust mode, the manual setting of the maximum value of the area of the exhaust nozzle.
An eighth object is to allow, for reverse mode, a locking means of the position of the reverser door pivots when the reverser door pivots have reached their deployed position, for deployment of the thrust reverser and for a portion of the transit of the reverser from its deployed to its stowed position.
A ninth object is to provide an automatic unlocking means of the position of the reverser door pivots, during transit to stow, for completion of the reverser stowing transit sequence, once the reverser door receptacles have re-engaged their respective fixed retainers.
A tenth object is to use the thrust reverser doors as the muscle for previous unlocking means.
Yet another object is to provide the same, or possibly improved protection against an inadvertent deployment of the reverser compared to the prior art.
A turbofan exhaust nozzle includes a jet pipe having a pair of thrust reverser doors disposed on opposite sides thereof. Each door has a hinge arm joined to a swing arm, which in turn is joined to the pipe. Each door also includes a latching clip at a forward end, and a deployment clevis between the clip and hinge arm. A common actuator is connected to both doors by corresponding links joined to the clevises for driving the links aft to pivot aft the doors and swing arms. A first lock selectively locks the latching clip and a second lock selectively locks the swing arms in coordination with the first lock for permitting variable area axial movement of the doors, thrust reverser deployment thereof, and retraction to stowed positions of the doors.